KR100853588B1 - Disc drive products including a method and circuit for operating a multiphase dc motor, a method for reducing acoustic noise when operating a multiphase dc motor, and a multiphase dc motor - Google Patents

Abstract

A method and circuit for operating a multiphase dc motor in which the drive voltage is applied to the windings of the motor in a predetermined phase is presented. The zero crossing of the current flow is detected at each winding of the motor, and the phase of the drive voltage is adjusted to zero crossing substantially simultaneously with the detected zero crossing of the current flow at each winding of the motor. The method includes generating these sets of three waveforms 45, 46, 47 to apply a drive voltage to each winding of the motor. Each waveform has a first segment 43 having a zero value for 120 °, a subsequent second segment 50 having a “up slope” shape for 60 °, two consecutive “caps” for 120 °. It has a 360 ° period with a subsequent third segment having a shape, a subsequent fourth segment 52 having a “down slope” shape with respect to 60 °. Each waveform of the set is moved 120 ° from each other. This reduces the acoustic motor noise.

Multiphase dc motor, up slope, down slope, cap, acoustic motor noise

Description

Disc drive products including a method and circuit for operating a multiphase dc motor, a method for reducing acoustic noise when the multiphase dc motor is operated, and a multiphase dc motor {SILENT SPIN SINE WAVE GENERATOR}

1 is an ideal drive signal waveform diagram suitable for a three phase dc motor;

2 is a block diagram of a portion of a circuit for applying a drive signal to a multiphase dc motor according to a preferred embodiment of the present invention.

3 is an "up slope" partial waveform diagram generated at the output of one of the MDAC circuits of FIG. 2 to approximate the ideal waveform of FIG. 1 in accordance with a preferred embodiment of the present invention.

4 is a "cap" partial waveform diagram generated at the output of the other of the MDAC circuits of FIG. 2 to approximate the ideal waveform of FIG. 1 in accordance with a preferred embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

12: "cap" MDAC

14: "Slope" MDAC

16: multiplexer

18: three phase dc motor

19: Disk of MDSD

21: Multiplexer Controller

22: clock generator

36: "cap" PWM modulator                 

38: "Slope" PWM Modulator

The present invention relates to a method and circuitry for driving a DC brushless polyphase motor, such as a spindle motor of a hard disk drive, and the like, in particular a driving method for reducing at least acoustic noise in this kind of motor. And an improvement in circuitry and a drive method and circuit for driving such a motor using a drive voltage which is a waveform approximation constructed substantially from a sinusoidal waveform segment, more specifically a drive voltage constructed from a substantially linear approximation of such waveform approximation. will be.

In the operation of a DC brushless polyphase motor of the type addressed by the present invention, effective motor drive requires that the excitation current applied to the motor phases be aligned with the bemf generated for each phase. One of the best structures to achieve this alignment is to use a phase locked loop that adjusts the phase and frequency of the commutation, allowing the bemf of the undriven winding to pass zero at the center of the appropriate rectification state. This structure works well when the shape of the commutation waveform includes an undriven region, as in the conventional six states, i.e., +1, +1, 0, -1, -1, 0 sequence.

Since the sequence +1, +1, 0, -1, -1, 0 has a sharp transition between driving states, this sequence has many high frequency components. These tend to excite mechanical resonances in the motor and cause undesirable acoustic noise to be generated. Furthermore, the step function tristate of the undriven motor phase, along with the step function waveform itself, causes some torque ripple in the motor. Torque ripple becomes uneven in motor rotation, excites resonance in the motor, and also generates undesirable acoustic noise.

Thus, if it is desirable to reduce acoustic noise, sinusoidal excitation signals are more suitable than six-state sequences. If the motor driver is configured with a sinusoidal current source, the same voltage sensing PLL described above can be used. However, when the driver's duty cycle changes sinusoidally, the motor driver excitation is pulse width modulated (PWM) to minimize power consumption in the driver IC. This lowers packaging costs and reduces system costs as a whole. In the past, however, it has been difficult to generate currents with pure sinusoidal waveforms, especially when the current is relatively high and when it is desirable to use a pulse width modulation scheme.

In US Application No. 09 / 300,754, after the initial baseline erase, the drive waveform consisted of consecutive concatenated segments that were zero for 120 °, "up hook" for 120 °, and "down hook" for 120 °. Up hook and down hook waveforms were generated in two MDACs. The operation of MDAC has a problem that it is difficult to form a desirable drive waveform. In particular, there was a need to create a circuit conflict so that the resulting waveform could operate properly in a multiphase DC motor environment.

In addition, forming waveform segments that form themselves from a sinusoidal waveform segment combination using a multiplying digital to analog converter (MDAC) requires special MDAC design and operation considerations. Designs that can be constructed from linear waveform segments such that the drive waveform approximates a sine wave segment combination will make implementation and operation of such MDAC significantly easier.

As a result, there is a need for a disk driver and method that operates by reducing or removing noise associated with driving during operation. There is a further need for a disk drive and method that employs a drive signal generated from a sinusoidal signal segment that can be easily approximated by a concatenated linear signal segment.

Accordingly, in view of the above, it is an object of the present invention to provide an improved disk drive and its method of operation that reduce or eliminate noise associated with the drive during operation.

It is another object of the present invention to provide a disk drive and method employing a multiple drive signal having segments having a substantially continuous chain waveform constructed from or approximating a segment of a sine signal.

Other objects, features and advantages of the present invention will become apparent to those skilled in the art from the following detailed description when read in conjunction with the accompanying drawings and claims.

에 근사하고, 여기에서 VMAG는 각 파형의 최대 진폭이고, ωt는 파형의 위상각이고, φ는 초기 위상각이지만, 바람직한 실시예에서 각각의 파형 세그먼트는 적어도 하나의 선형 파형을 포함한다. 바람직하게는, 파형 세그먼트는 중심부에 브레이크포인트(breakpoint)를 갖는 2개의 선형부를 가질 수 있다.Thus, according to a broad aspect of the present invention, a method of operating a three phase dc motor is presented. The method includes generating a set of three waveforms to apply a drive voltage to each winding of the motor. Each waveform is a first segment having a zero value for 120 °, a subsequent second segment having an "up slope" shape for 60 °, a subsequent second having two consecutive "cap" shapes for 120 °. 3 segments, 360 ° period with a subsequent fourth segment having a “down slope” shape for 60 °. Each waveform of the set is displaced by 120 ° from each other. The waveform is then applied to each winding of the motor. Each segment

Approximate to, where VMAG is the maximum amplitude of each waveform, ωt is the phase angle of the waveform, and φ is the initial phase angle, but in a preferred embodiment each waveform segment comprises at least one linear waveform. Preferably, the waveform segment may have two linear portions with breakpoints in the center.

According to a broad aspect of the present invention, a method of reducing acoustic noise in operating a multiphase dc motor is presented. The method includes generating a set of n waveforms to apply a drive voltage to the windings of each motor, where n is the number of phases of the multiphase dc motor. Each waveform has a 360 ° period, a first segment having a zero value for (360 / n) °, a subsequent second segment having a "up slope" shape for (360 / 2n) °, (360 / n) has a subsequent third segment having two consecutive "cap" shapes for °, a subsequent fourth segment having a "down slope" shape for (360 / 2n) °. Each waveform of the set is displaced by (360 / n) ° from each other. The waveform is applied to each winding of the motor to drive the motor. The waveform can be pulse width modulated prior to application to the driver.

Each segment                         

에 근사할 수 있고, 여기에서 VMAG는 각 파형의 최대 진폭이고, n은 상기 모터의 위상 수이고, ωt는 파형의 위상각이고, φ는 초기 위상각이다. 파형 세그먼트는 적어도 하나의 선형 파형을 포함할 수 있고, 더 상세하게는 파형 세그먼트의 각각은 중심부에 브레이크포인트를 갖는 2개의 선형부를 가질 수 있다.

Can be approximated to, where VMAG is the maximum amplitude of each waveform, n is the number of phases of the motor, ωt is the phase angle of the waveform, and φ is the initial phase angle. The waveform segment may comprise at least one linear waveform, and more specifically, each of the waveform segments may have two linear portions with breakpoints in the center.

According to another broad aspect of the present invention, a circuit for operating an n-phase dc motor is presented. The circuit has a driver for applying an n drive signal waveform to the motor. A source of drive signal waveforms is provided. Each drive signal waveform has a first segment having a zero value for (360 / n) °, a subsequent second segment having an "up slope" shape for (360 / 2n) °, and (360 / n) °. With a subsequent third segment having two consecutive "cap" shapes for, a subsequent fourth segment having a "down slope" shape for (360 / 2n) °. Each waveform of the set is displaced by (360 / n) ° from each other. The drive signal waveform may comprise two linear portions having a substantially linear segment, more specifically, a breakpoint at the center thereof. Circuitry may also be provided to pulse width modulate the drive signal waveform prior to application to the driver.

Each segment

에 근사할 수 있고, 여기에서 VMAG는 각각의 파형의 최대 진폭이고, ωt는 파형의 위상각이고, φ는 초기 위상각이다.

Can be approximated to, where VMAG is the maximum amplitude of each waveform, ωt is the phase angle of the waveform, and φ is the initial phase angle.

에 근사할 수 있고, 여기에서 VMAG는 각각의 파형의 최대 진폭이고, ωt는 파형의 위상각이고, φ는 초기 위상각이다.According to another broad aspect of the present invention, a disk drive product of the type having a dc brushless, Hall-less, three-phase motor for rotating a medium containing data is presented. The product includes three driver circuits that apply a drive signal to each selected set of windings in the motor. 3 The source of the motor drive voltage waveform provides the drive signal. Each waveform has a 360 ° period. The first segment has zero value for 120 °. The second segment has a "up slope" shape for 60 °. The third segment has two consecutive "cap" shapes for 120 ° and the fourth segment has a "down slope" shape for 60 °. Each waveform of the set is displaced from each other by 120 ° from each other. The drive signal waveform is formed of substantially linear segments, more specifically two linear portions with breakpoints in the center. Each segment

Can be approximated to, where VMAG is the maximum amplitude of each waveform, ωt is the phase angle of the waveform, and φ is the initial phase angle.

In the various figures, like reference numerals are used to indicate same or similar parts.

According to a preferred embodiment of the invention, the drive waveforms applied to the windings of the motor to be driven are derived from the sinusoidal waveform in the manner disclosed in US patent application 09 / 300,754. The motor is of the type described above and may in particular be of the multiphase DC motor type described in the above-mentioned US patent application 09 / 300,754. In the illustrated embodiment, the motor is preferably a three phase DC motor.

In the illustrated embodiment, three signals are defined, each of which is displaced by 120 ° from each other to drive each phase of the motor. It should be noted that the motor windings do not need to drive each node with a pure sine wave because two of the three coil winding nodes of the "Y" coil structure are driven and one is used as a sink. It is sufficient if the voltage difference between the two driven nodes is substantially sinusoidal. A graph showing three consecutive drive waveforms 45, 46, 47 according to a preferred embodiment of the present invention is shown in FIG. 1. Each waveform 45, 46, 47 is applied to a pair commutatively determined of the input terminals of the motor to be driven, respectively.

에 근사할 수 있으며, 여기에서 VMAG는 각각의 파형의 최대 진폭이며, n은 모터의 위상의 수이며, ωt는 파형의 위상각이고, φ는 초기 위상각이다. 각각의 파형은 업훅부(40) 및 다운훅부(42)를 갖는다. 따라서, 사인파 세그먼트처럼 보이지만, 구동 파형 세그먼트는 실제로는 사인파 세그먼트가 아니다. 더욱이, 각각의 모터 위상은 정류 사이클의 120°에 대해 3상태로 되며, 각각의 파형은 120°에 대해 제로인 세그먼트(43)를 갖는다.In order to construct the drive waveforms 45, 46, 47, the value of the sine waveform having the instantaneous minimum value among the sine wave sets 120 degrees out of phase with each other is subtracted from the other waveforms. The set of waveforms shown in FIG. 1 is consequently similar to the set of waveforms disclosed in US patent application 09 / 300,754. Thus, each segment

Where VMAG is the maximum amplitude of each waveform, n is the number of phases of the motor, ωt is the phase angle of the waveform, and φ is the initial phase angle. Each waveform has an uphook portion 40 and a downhook portion 42. Thus, although it looks like a sinusoidal segment, the drive waveform segment is not actually a sinusoidal segment. Moreover, each motor phase is in three states for 120 ° of the commutation cycle, and each waveform has a segment 43 that is zero for 120 °.

A portion 10 of a circuit for applying a drive signal to a multiphase dc motor in accordance with a preferred embodiment of the present invention is shown in FIG. The circuit includes a "cap" generation MDAC 12 and a "slope" generation MDAC 14, which are described in detail below. The cap and slope MDACs 12 and 14 are updated once each PMW CLK cycle to provide shaped signals for selection by the multiplexer 16 for application to the three phase dc motor 18. The dc motor 18 rotates the spindle of the disk 19 used for a mass data storage device, for example. If desired, the output of MDAC 12, 14 can be pulse width modulated in a known manner by PWM modulators 36, 38 as shown, thereby controlling the power applied to motor 18.

MDAC 14 generates a signal at its output having a slope waveform that can be induced to approximate a segment of a sine wave, in particular a 60 ° segment of the sine wave. MDAC 14 may generate segments in ascending or descending order such that the ascending waveform substantially follows the “up-slope” segment 50 shown in FIG. 1, or the descending waveform is likewise shown in FIG. 1. Substantially follow the "down-slope" segment. If the period of the waveform is considered 360 °, the "up-slope" segment 50 or "down-slope" segment 52 is (360 / 2n) ° in length, where n is the number of phases of the motor.

The waveform generated by the " slope " MDAC 14 is preferably a linear waveform, as shown, for example, by waveform 60 in FIG. As shown, waveform 60 includes a breakpoint 62 about halfway between the top and bottom of the waveform, so that the overall shape of each half of waveform 60 is the "up-slope" shown in FIG. It is almost the same curve as the "segment 50" or "down-slope" segment 52. One of the advantages of using linear waveforms in the operation of MDAC 14 is that such waveforms can be easily generated by providing a linear counter that selectively counts up or counts down at a predetermined rate.

If desired, MDAC 14 may include a scaling circuit that determines the overall amplitude of waveform 60 generated. The scaling circuit can include, for example, a plurality of current generators that can be individually addressably selected to provide the biasing current required for generation of the desired waveform. Also, if desired, waveform 60 may be generated by subtracting the count value from the predetermined bias value.

Similarly, the "cap" MDAC 12 may be configured to generate two consecutive "cap" waveforms 65, 66 as shown in FIG. Each “cap” waveform 65, 66 is formed by a linear up count at break point 68, followed by a linear down count to its original starting value. The resulting waveforms 65, 66 correspond to the waveforms 67, 68 in FIG. 1. Again, by using a linear waveform technique with, for example, a linear up and down counter, the sine wave segments 67 and 68 can be easily approximated. Also, if desired, scaling circuitry may be included in MDAC 12, such that the overall scale of the waveform may be determined by, for example, an addressing circuitry or the like. If the waveform has a period of 360 °, each cap segment can be a length (360 / 2n) ° over the entire length (360 / n) °, where n is the number of motor phases.

The output from each MDAC 12, 14 is selectively applied by the multiplexer circuit 16 to the motor control lines 30-32 for application to the three phase motor 18. The multiplexer circuit 16 is controlled by the multiplexer controller 21, which receives the clock pulses from the clock generator 22 divided by the divider circuit 24. For example, the multiplexer controller 21 may be an address circuit that repeatedly applies an address to the multiplexer 16 to generate the repetitive waveforms 45-47 shown in FIG. 1.

If desired, as shown, the output from MDAC 12, 14 may be pulse width modulated by, for example, each PWM modulator 36, 38 shown. Pulse width modulation can be performed by known methods. Typically, a triangle wave is used as a pass waveform so that the signal being modulated is transmitted only when it is greater than the value of the instantaneous triangle wave. One of the advantages that can be realized using the circuit of FIG. 2 is that a common clock signal derived from clock generator 22 can be used to generate linear waveform segments in MDAC circuits 12 and 14, as described above. Since the same clock signal can be used to control the timing of the pulse width modulation of the pulse width modulators 36, 38, each waveform generated by the MDAC is applied to the signals applied to the three phase motor 18. It can be easily adjusted to avoid delays and discontinuities.

While the present invention has been described and illustrated at a particular angle, the present disclosure has been made by way of example only, and various changes in combination and arrangement of parts may be made by one skilled in the art without departing from the spirit and scope of the claims to be described below.

According to the present invention, a multiple drive signal having a segment having a substantially continuous chain waveform constructed from a sine signal segment or approximating a segment of a sine signal can reduce or eliminate noise associated with driving during operation of the disk driver. Can be adopted.

Claims (26)

As a method of operating a multiphase dc motor, Generating a set of three waveforms to apply a drive voltage to each winding of the motor, each waveform having a first segment having a zero value for 120 °, followed by a “up slope” shape for 60 ° The set has a 360 ° period with a second segment, a subsequent third segment having two consecutive “cap” shapes for 120 °, a subsequent fourth segment having a “down slope” shape for 60 °, and the set Each waveform is displaced by 120 ° from each other; And Applying the waveform to the respective windings of the motor Method for operating a multiphase dc motor comprising a. 2. The method of claim 1 further comprising pulse width modulating the drive voltage prior to application to the motor windings. The method of claim 1, wherein each of the segments

Nice to, and here VMAG is the maximum amplitude of each waveform, ωt is the phase angle of the waveform, φ is the initial phase angle how the multiphase dc motor operates. 2. The method of claim 1 wherein each of the waveform segments comprises at least one linear waveform. 5. The method of claim 4, wherein each of said waveform segments has two linear portions having a breakpoint at its center. As a method of reducing acoustic noise in operating a multiphase dc motor, Generating a set of n waveforms to apply a drive voltage to each winding of the motor, where n is the number of phases of the multiphase dc motor, each waveform having a zero value for (360 / n) ° One segment, subsequent second segment having an "up slope" shape for (360 / 2n) °, subsequent third segment having two consecutive "cap" shapes for (360 / n) °, ( Having a 360 ° period with a subsequent fourth segment having a “down slope” shape for 360 / 2n) °, each waveform of the set being displaced by (360 / n) ° from each other; And Applying the waveform to the respective windings of the motor Acoustic noise reduction method when operating a multiphase dc motor comprising a. 7. The method of claim 6, further comprising pulse width modulating the drive voltage prior to application to the winding. The method of claim 6, wherein each of the segments

Nice to, and here VMAG is the maximum amplitude of each waveform, n is the number of phases of the motor, ωt is the phase angle of the waveform, φ is the initial phase angle acoustic noise reduction method. 7. The method of claim 6, wherein each of the waveform segments comprises at least one linear waveform. 10. The method of claim 9, wherein each of the waveform segments has two linear portions having a breakpoint at the center thereof. A circuit that operates an n-phase dc motor, Drivers for applying n drive signal waveforms to the motor; And Source of the drive signal waveforms Including, Each waveform is for a first segment having a zero value for (360 / n) °, for a subsequent second segment having an "up slope" shape for (360 / 2n) °, for (360 / n) °. Each waveform in the set having a 360 ° period with a subsequent third segment having two consecutive “cap” shapes, a subsequent fourth segment having a “down slope” shape for (360 / 2n) °, Is a dc motor operating circuit that is displaced by (360 / n) °. 12. The dc motor operating circuit of claim 11, wherein the source of the drive signal waveform is a first MDAC that generates the "up slope" and a "down slope" waveform and a second MDAC that generates the "cap" shaped waveforms. The dc motor operating circuit of claim 12, wherein the drive signal waveform comprises a linear segment. The dc motor operating circuit of claim 13, wherein each of the waveforms has two linear portions having a breakpoint at the center. 12. The dc motor operating circuit of claim 11, further comprising a multiplexer connected to receive the outputs of the MDACs, wherein the multiplexer is operative to selectively apply the outputs of the MDACs to the drivers. 12. The dc motor operating circuit of claim 11, further comprising circuitry for pulse width modulating a drive signal waveform prior to application to the drivers. The dc motor operating circuit of claim 11, wherein n is three. The method of claim 11, wherein each of the segments

Nice to, and here VMAG is the maximum amplitude of each waveform, ωt is the phase angle of the waveform, φ is dc motor operation circuit which is initial phase angle. It is a type of disk drive with a dc brushless, Hallless, three-phase motor that rotates data bearing media. Three driver circuits for applying drive signals to each selected set of windings of the motor; Source of three motor drive voltage waveforms for applying the drive signals Including, Each waveform is a first segment having a zero value for 120 °, a subsequent second segment having an "up slope" shape for 60 °, a subsequent second having two consecutive "cap" shapes for 120 °. A disk drive product having a 360 ° period with three segments, a subsequent fourth segment having a “down slope” shape for 60 °, each waveform of the set being displaced by 120 ° from each other. 20. The disk drive product of claim 19, wherein each of the driver circuits comprises a pair of FETs connected in series between a power supply and a reference potential, together at a drive signal node. 20. The disk drive product of claim 19, further comprising a multiplexer connected to receive the motor drive voltage waveforms and to selectively apply the motor drive voltage waveforms to the driver circuits. 20. The disk drive product of claim 19, further comprising circuitry for pulse width modulating the motor drive voltage waveform prior to application to the drive circuits. 20. The disk drive product of claim 19, wherein the drive signal voltage waveforms comprise linear segments. The disk drive product of claim 23, wherein each of the waveforms has two linear portions having a breakpoint at the center thereof. The method of claim 24, wherein each of the segments is

Nice to, and here VMAG is the maximum amplitude of each waveform, ωt is the phase angle of the waveform, φ is the disc drive product which is the initial phase angle. 20. The disk drive product of claim 19, wherein the data bearing medium is a magnetic medium of a hard disk drive.

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